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of: Allow busses with #size-cells=0

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It's quite legitimate for a DT node to specify #size-cells=0. One example
is a node that's used to collect a number of non-memory-mapped devices.
In that scenario, there may be multiple child nodes with the same name
(type) thus necessitating the use of unit addresses in node names, and
reg properties:

/ {
	regulators {
		compatible = "simple-bus";
		#address-cells = <1>;
		#size-cells = <0>;

		regulator@0 {
			compatible = "regulator-fixed";
			reg = <0>;
			...
		};

		regulator@1 {
			compatible = "regulator-fixed";
			reg = <1>;
			...
		};

		...
	};
};

However, #size-cells=0 prevents translation of reg property values into
the parent node's address space. In turn, this triggers the kernel to
emit error messages during boot, such as:

    prom_parse: Bad cell count for /regulators/regulator@0

To prevent printing these error messages for legitimate DT content, a
number of changes are made:

1) of_get_address()/of_get_pci_address() are modified only to validate
   the value of #address-cells, and not #size-cells.

2) of_can_translate_address() is added to indicate whether address
   translation is possible.

3) of_device_make_bus_id() is modified to name devices based on the
   translated address only where possible, and otherwise fall back to
   using the (first cell of the) raw untranslated address.

4) of_device_alloc() is modified to create memory resources for a device
   only if the address can be translated into the CPU's address space.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
This commit is contained in:
Stephen Warren
2012-07-25 17:34:37 -06:00
committed by Rob Herring
parent 0d7614f09c
commit 5d61b165c8
3 changed files with 37 additions and 7 deletions
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16
drivers/of/platform.c
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@@ -78,6 +78,7 @@ void of_device_make_bus_id(struct device *dev)
struct device_node *node = dev->of_node;
const u32 *reg;
u64 addr;
const __be32 *addrp;
int magic;
#ifdef CONFIG_PPC_DCR
@@ -105,7 +106,15 @@ void of_device_make_bus_id(struct device *dev)
*/
reg = of_get_property(node, "reg", NULL);
if (reg) {
addr = of_translate_address(node, reg);
if (of_can_translate_address(node)) {
addr = of_translate_address(node, reg);
} else {
addrp = of_get_address(node, 0, NULL, NULL);
if (addrp)
addr = of_read_number(addrp, 1);
else
addr = OF_BAD_ADDR;
}
if (addr != OF_BAD_ADDR) {
dev_set_name(dev, "%llx.%s",
(unsigned long long)addr, node->name);
@@ -140,8 +149,9 @@ struct platform_device *of_device_alloc(struct device_node *np,
return NULL;
/* count the io and irq resources */
while (of_address_to_resource(np, num_reg, &temp_res) == 0)
num_reg++;
if (of_can_translate_address(np))
while (of_address_to_resource(np, num_reg, &temp_res) == 0)
num_reg++;
num_irq = of_irq_count(np);
/* Populate the resource table */